Myriophyllum quitense
Myriophyllum alterniflorum
Andean water-milfoil, waterwort milfoil, waterwort water-milfoil
alternate-flower water-milfoil, myriophylle à fleurs alternes
often branched, to 3 m. Turions absent.
often branched, to 2.5 m. Turions absent.
mostly in whorls of (3 or)4(or 5), sometimes opposite to subopposite, heteromorphic;
petiole 0–4 mm; submersed leaves pectinate to lobed (basalmost leaves opposite to subopposite, reduced, margins entire), ovate to obovate in outline, (3–)5–25(–35) × (2–)3–18(–20) mm, segments (2 or)3–9(–11), linear, ± applanate, longest segment (7–)8–15(–17) mm; emersed leaves pinnatisect to lobed or entire, ovate to oblong in outline, 2–9 × 1–6 mm, margins dentate to minutely serrate.
usually in whorls of 3 or 4(or 5), rarely opposite, distal emersed leaves alternate, heteromorphic;
petiole 0–0.5 mm; submersed leaves pectinate, ovate to elliptic or obovate in outline, 3–16(–40) × (3–)4–10(–14) mm, segments 6–16(–20), linear-filiform, longest segment 2–11(–15) mm; emersed leaves elliptic to oblanceolate or spatulate proximally, pectinate to pinnatifid distally, 0.7–2 × 0.3–0.5 mm, segments 0–10(–12), margins ± serrate to shallowly lobed.
to 8 cm;
flowers proximally pistillate, medially bisexual, distally staminate;
bracteoles cream, deltate, 0.5–1 × 0.2–0.6 mm, margins dentate to serrate, with glandular tip.
to 12 cm;
flowers proximally pistillate, in whorls of 4, often medially bisexual, distally staminate from alternate bracts;
bracteoles cream to stramineous, with distinct brown to purple margins, ovate to depressed-ovate, 0.2–0.5 × 0.2–0.5 mm, margins serrate to irregularly fringed, apex often aristate.
sepals green to cream, ovate to deltate, (0.2–)0.3–0.5(–0.7) × (0.1–)0.2–0.4(–0.5) mm;
petals persistent, ± purple, oblong, 2–3 × 0.5–1.5 mm;
stamens 8, filaments to 0.6 mm, anthers 1.8–2.5 × 0.2–0.6 mm.
sepals cream to stramineous, narrowly triangular, 0.1–0.2 × 0.1 mm;
petals caducous, cream, elliptic to obovate, (0.7–)1.3–1.8 × (0.4–)0.6–1 mm;
stamens 8, filaments to 0.6 mm, anthers cream to purple, 1.1–1.5 ×0.2–0.4 mm.
sepals cream, deltate, 0.2–0.5 × 0.1–0.4 mm;
petals ± persistent, cream, ± cucullate, elliptic, 0.1–0.5 × 0.2–0.3 mm;
pistils 1.1–2.2 mm, stigmas cream to ± purple, to 0.6 mm.
sepals cream, lanceolate to triangular or deltate, 0.1–0.2 × 0.1 mm;
petals usually caducous, rarely persistent, cream, widely ovate, 0.2–0.4 × 0.2–0.3 mm;
pistils 0.7–1.1 mm, stigmas red to ± purple, pulvinate, to 0.3 mm.
cylindric to oblong, 4-lobed.
ovoid, 4-lobed.
tan to olive-brown, cylindric to ovoid, 1.5–1.8 × 0.6–0.8 mm, transversely elliptic, abaxial surface rounded, smooth, sometimes with a shallow, longitudinal ridge, wings and ribs absent.
olive-green to red-brown, cylindric to narrowly ovoid, 1.3–1.6 × 0.3–0.4 mm, transversely widely obovate, abaxial surface broadly rounded, irregularly to densely papillate, sometimes with orange to red, punctate trichomes, wings and ridges absent.
= 42.
= 14.
Myriophyllum quitense
Myriophyllum alterniflorum
The most distinguishing feature of Myriophyllum quitense is the production of relatively large, ovate distal floral bracts with serrate margins. This characteristic is shared only with M. heterophyllum; however, M. quitense has eight stamens and the latter has four.
The proximal submersed leaves of most Myriophyllum species are uniformly pectinate, but those of M. quitense can range from entire or lobed to pectinate. This species often exhibits a pronounced transition from three or four proximal nodes of large, opposite, spatulate or lobed prophylls, to nodes of besomiform whorled leaves having obtriangular laminar surfaces and distal pinnatifid segments resembling those of pectinate leaves. In addition, the unusual grayish blue color of the foliage and whitish rhizomes are useful characteristics for distinguishing submersed vegetative specimens of M. quitense from similar species, such as M. sibiricum.
Myriophyllum quitense has a highly disjunct distribution in North America and South America (A. E. Orchard 1981; O. Ceska et al. 1986). S. G. Aiken (1981) and R. Couch and E. Nelson (1988) suggested that M. quitense was introduced into North America by migratory waterfowl. Both Ceska et al. and M. L. Moody and D. H. Les (2010) regarded it as native to North America. It has been reported from New Brunswick and Prince Edward Island (D. F. McAlpine et al. 2007) and further range extensions would seem likely given the level of disjunction in distribution.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Myriophyllum alterniflorum is distinguished in flower and fruit by minute, alternate, entire distal floral bracts, a characteristic shared only with M. laxum. Unlike the flowers of other Myriophyllum species in the flora, those of M. alterniflorum are widely scattered along the inflorescence and the tip of the spike is often nutant. The pistils are relatively small, each having a prominent, purple, pulvinate stigma that is as broad as or broader than the ovary and persistent in fruit. The pistil and mericarp surface has scattered orange to red punctate trichomes not seen on the pistils or mericarps of any other water-milfoil in the flora area. The cream, depressed-ovate, fringed, often aristate bracteoles with brown to red margins are also distinctive. Seed-set appears to be rare in M. alterniflorum. Specimens examined from Greenland far exceed other North American plants in the size of their leaves and staminate flowers. North American plants with relatively short leaves and a bushy habit have been referred to as var. americanum. Plants of this form can be confused with the relatively small M. sibiricum and M. verticillatum in northern latitudes but are distinguishable based on floral characters. Leaf size in M. alterniflorum is plastic and continuous in variation, thus varieties are not recognized here as separate taxa.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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